1. Field of the Invention
The present invention relates to a device for determining the swing speed of rotatable implements such as human activated sporting goods, viz: a bat, a tennis racquet, etc.
2. Description of the Prior Art
To measure speed or the like at the time of swinging of sporting goods such as a golf club, a bat, a tennis racket, etc., there have been heretofore proposed devices which can be directly mounted on the goods. Such devices include, for example, a pointer-movable type in which a spring within the mounted device is extended by a centrifugal force produced at the time of swing to move a pointer, and after swinging has been finished, the spring is returned to its original position with the result that the pointer remains stopped at a position to which it has moved to determine the maximum centrifugal force (head speed) (see Japanese Utility Model Application Laid-open Nos. 60-7,858 and 60-32,972); a system in which the sound through the air is produced by air resistance caused by swinging (see Japanese Utility Model Application No. 60-30,267); and a system in which a propeller is provided, and a measured value is calculated from rotation of the propeller (see Japanese Patent Publication No. 51-10,536).
However, the above-described conventional devices have been proposed to measure a swing speed to calculate a distance covered or flown, or to merely decide whether or not a set swing speed was reached, but were not possible to find whether or not the maximum speed (maximum acceleration) was reached at a reasonable position in a swinging orbit. That is, there have been encountered problems wherein swinging in the proper form cannot be determined, and therefore, a player is apt to swing with all his strength and when measurement is made, his swing form tends to get out of shape.